1. Field of the Invention
The present invention relates to a method for polishing disk shaped workpieces, in particular for the single side polishing of semiconductor wafers. The invention also relates to a device which is suitable for carrying out the method.
2. The Prior Art
During the single side polishing of semiconductor wafers, the rear sides of the semiconductor wafers are fixed onto carrier plates. The front sides of the semiconductor wafers are polished, by having a plurality of carrier plates pressed against a polishing plate, over which a polishing cloth is stretched. The polishing then occurs by means of polishing heads of a polishing machine. The polishing plate and the carrier plates rotate during the polishing. Usually, before a polishing operation takes place, a manipulator transfers the carrier plates, which are covered with the fixed semiconductor wafers, to the polishing heads. This manipulator receives them again following the polishing operation. The carrier plates are transferred sequentially. The polishing heads are brought together in a polishing-plate superstructure. The polishing plate and the polishing-plate superstructure are supported on a common machine frame.
The prior art method and the use of the polishing machines described only permits the obtaining of semiconductor wafers with smooth and planar front sides achieved to a limited extent.
It is an object of the present invention to provide a modified polishing method and a device for carrying out this method which method avoids the drawbacks associated with known polishing methods and polishing machines.
The present invention relates to a method for polishing disk shaped objects, in particular semiconductor wafers, which are fixed on carrier plates. The carrier plates are pressed against a polishing plate, over which a polishing cloth is stretched, by means of polishing heads. The polishing heads are accommodated in a polishing-plate superstructure, wherein the carrier plates, following a polishing operation, are simultaneously lifted off the polishing plate by means of lifting devices in the polishing heads. The polishing-plate superstructure is displaced, together with the carrier plates, along a linear guide above a polishing line.
The method is distinguished by the fact that the workpieces are treated absolutely uniformly due to the simultaneous manipulation of the carrier plates. As a result, the planarity values, for example, of the polished sides of the wafers are much more uniform from one wafer to the next wafer.
The invention also relates to a device for carrying out the method, wherein lifting devices, by means of which the carrier plates can be simultaneously lifted off the polishing plate, are provided in the polishing heads, and the polishing-plate superstructure can be displaced, together with the carrier plates, along a linear guide above a polishing line.